| 摘要 |
PURPOSE:To realize a filter which can eliminate high Q mechanical resonance efficiently by a method wherein a number, equal to the number of resonance points, of notch filters having built-in switched capacitor integrators are connected in series to a first order time-lag filter. CONSTITUTION:A first order time-lag filter 10 attenuates a signal by, for instance, about 10dB in a frequency band of 20-200Hz. Notch filters(NF) 20 and 30 are connected in series to the first order time-lag filter 72. The NF 20 is composed of a subtractor 21, switched capacitor integrators 22 and 23 and a coefficient unit 24. The difference in output between the first order time- lag filter 10 and the coefficient unit 24 is amplified by the subtractor 21, integrated by the integrator 22 and inputted to the coefficient unit 24. At the same time, the difference in output is integrated by the integrator 23 and fed back to the integrator 22. The coefficient unit 24 multiplies the output of the integrator 22 by 1/Q1. The value Q1 is so predetermined as to suppress the Q value at a first resonance point. The NF 30 has a construction similar to that of the NF 20. The subtractor 31 amplifies the difference in output between the subtractor 21 and the coefficient unit 34 and outputs (V0) it. With this constitution, a plurality of high Q mechanical resonances can efficiently be eliminated. |
